--- /dev/null
+/*
+ * compat_futex.c
+ *
+ * Userspace RCU library - sys_futex compatibility code
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdio.h>
+#include <pthread.h>
+#include <signal.h>
+#include <assert.h>
+#include <errno.h>
+#include <poll.h>
+
+#include <urcu/arch.h>
+#include <urcu/urcu-futex.h>
+
+static pthread_mutex_t compat_futex_lock = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t compat_futex_cond = PTHREAD_COND_INITIALIZER;
+
+/*
+ * _NOT SIGNAL-SAFE_. pthread_cond is not signal-safe anyway. Though.
+ * For now, timeout, uaddr2 and val3 are unused.
+ * Waiter will relinquish the CPU until woken up.
+ */
+
+int compat_futex_noasync(int *uaddr, int op, int val,
+ const struct timespec *timeout, int *uaddr2, int val3)
+{
+ int ret, i, gret = 0;
+
+ /*
+ * Check if NULL. Don't let users expect that they are taken into
+ * account.
+ */
+ assert(!timeout);
+ assert(!uaddr2);
+ assert(!val3);
+
+ /*
+ * memory barriers to serialize with the previous uaddr modification.
+ */
+ smp_mb();
+
+ ret = pthread_mutex_lock(&compat_futex_lock);
+ assert(!ret);
+ switch (op) {
+ case FUTEX_WAIT:
+ if (*uaddr != val)
+ goto end;
+ pthread_cond_wait(&compat_futex_cond, &compat_futex_lock);
+ break;
+ case FUTEX_WAKE:
+ for (i = 0; i < val; i++)
+ pthread_cond_signal(&compat_futex_cond);
+ break;
+ default:
+ gret = -EINVAL;
+ }
+end:
+ ret = pthread_mutex_unlock(&compat_futex_lock);
+ assert(!ret);
+ return gret;
+}
+
+/*
+ * _ASYNC SIGNAL-SAFE_.
+ * For now, timeout, uaddr2 and val3 are unused.
+ * Waiter will busy-loop trying to read the condition.
+ */
+
+int compat_futex_async(int *uaddr, int op, int val,
+ const struct timespec *timeout, int *uaddr2, int val3)
+{
+ int ret, i;
+
+ /*
+ * Check if NULL. Don't let users expect that they are taken into
+ * account.
+ */
+ assert(!timeout);
+ assert(!uaddr2);
+ assert(!val3);
+
+ /*
+ * Ensure previous memory operations on uaddr have completed.
+ */
+ smp_mb();
+
+ switch (op) {
+ case FUTEX_WAIT:
+ while (*uaddr == val)
+ poll(NULL, 0, 10);
+ break;
+ case FUTEX_WAKE:
+ break;
+ default:
+ return -EINVAL;
+ }
+}